Prostate cancer is a cancer of the prostate gland, a small, walnut-sized structure making up a part of a man's reproductive system that wraps around the urethra. Early detection of prostate cancer, for example, prior to presentation of symptoms, can improve patient prognosis. It is estimated that there are 200,000 new cases and 25,000 deaths from prostate cancer each year in the United States. Jemal A, et al. C A Cancer J Clin. 2008; 58(2):71-96. Cancer cells with a Gleason grade 3 or 4 generally indicate aggressive cancers that require treatment. The prostate-specific antigen (PSA) test measures the amount of PSA in a blood sample of a patient and is used to determine if a patient should receive a biopsy test. However, the PSA test detects both benign prostate hyperplasia (BPH) and prostate cancer, therefore only 20-30% of biopsies are found to be positive for cancer. Out of those patients with negative results from a first biopsy, approximately 10% of second biopsies are found to be positive for cancer. Guyon, I. et al. Urotoday Int J. 2009 Aug.; 2(4). In addition, biopsy is an invasive procedure that can result in complications such as septicemia, infections, hemorrhages, hematomas, arteriovenous fistula, tumor dissemination, bladder perforation, urinary obstruction, severe pain, strokes, perineum abscesses, erectile dysfunction, loss of desire and reduced sexual activity.